Investigations into last October's Singapore Airlines crash in Taiwan have revealed that airport officials failed to mark a closed runway properly.

The accident, which left 83 people dead, happened when the Boeing 747 slammed into construction equipment and burst into flames as it tried to take off from a runway closed for repairs at Taipei's Chiang Kai-shek airport.

There should have been a marking that the runway was closed

Investigator Kay Yong

A preliminary report indicates that one runway light was broken and the other not bright enough at the time of the accident, which took place amid reduced visibility caused by a heavy rainstorm.

Despite their criticism of the airport, investigators did not clearly pin the blame on the authorities there, noting that pilot error was still a principal factor.

Investigators said the closed runway should have had a big cross marked on it, warning planes not to use it.

"There are some areas that did not meet international standards... It is an old airport built in 1979," Kay Yong, director of the Aviation Safety Council, said.

Airport officials, however, have said that they followed international marking and lighting standards for the runway.

Pilot error

Mr Kay stressed they were not ready to formally announce what was behind the crash, saying they were merely "presenting all facts gathered" and leaving it up to prosecutors to draw final conclusions.

The report also described how the pilots took a wrong turning when taxirng before take-off.

The plane crashed into construction equipment

"Flight SQ006 received permission from the control tower for takeoff from 05L runway... and made confirmation," the report said.

"But flying data showed that the aircraft turned to 05R runway."

He said the final report could be released by December.

Singapore Airlines has accepted full responsibility for the crash, offering compensation to the injured and families of the victims, but also called for a review of facilities at Chiang Kai-shek airport.

Lawsuits

Until the Taipei crash, the airline had long been considered one of the world's safest, without a fatal accident in its 28-year history.

Rescuers approached the fuselage once the fire had been put out

Taiwan prosecutors had threatened to take legal action against the three pilots involved who survived the crash if they were found responsible for the tragedy.

They were allowed to return to Singapore in December after more than seven weeks of detention in Taipei.

If convicted of manslaughter, they could be jailed for up to five years.

A number of passengers have filed suits against the airline and pilots.

The aircraft, with 179 people on board, was taking off for Los Angeles.